1. Field of the Invention
The present invention is broadly concerned with improved adjustment apparatus, preferably in the form of an impact micrometer designed for limiting the stroke lengths of die cutting presses or other forming machines. More particularly, the invention pertains to apparatus of this type which are especially constructed to absorb impact loads without damage to the micrometer threading thereof. This is accomplished by reducing the load area of the adjustment mechanism relative to the total load-bearing area of the micrometer using a sealed fluid-filled chamber to transfer loads to the adjustment mechanism.
2. Description of Prior Art
In the operation of conventional die cutting presses, a die set is positioned between a movable ram and a fixed bolster plate, and the ram is repeatedly moved toward the fixed bolster to perform cutting operations on workpieces. In order to properly die cut the workpiece and prevent damage to the die set, it is necessary to closely control the stroke length of the ram. That is, if the stroke length is too long, the resultant die cut may be too deep, and/or the die carried by the die set may be damaged or ruined. Likewise, if the stroke length is too short, the workpiece will be insufficiently cut. In addition to the need for controlling ram stroke length, it is often necessary to adjust the stroke length for different types of workpieces or operating conditions.
It has been known in the past to use stops in die cutting presses for controlling stroke length. If adjustability of the stops is not a concern, then a variety of conventional stop configurations can be used. However, if fine micrometer-scale adjustment of stroke length is required, a severe problem is presented. On the one hand, the stops need to be robust enough to withstand millions of impact cycles, and on the other need to be finely adjustable (0.0001" resolution), implying the need for fine micrometer threading as a part of the adjustment mechanism. If typical fine threaded micrometers are employed as a part of the stops, the rather severe and repeated impact loads developed during die cutting operations can very quickly destroy the micrometer threading. This results because virtually all of the impact loads are transmitted to the threading in such conventional micrometer designs.